The writer is a science commentator

Every emerging technology has its dreamers and schemers. That is certainly true of human genome editing, the focus of a high-profile global summit held this week at the Francis Crick Institute in London.

Among the dreamers is Harvard University biochemist David Liu, whose talk on Monday featured news of Alyssa, a British teenager now in remission from leukaemia after receiving donated T-cells edited using a technique developed in his lab.

The most notorious schemer is He Jiankui. In November 2018, he revealed he had altered the DNA of early embryos which were implanted in women, leading to the world’s first three genome edited babies. His secret, technically premature project — intended to make the infants immune to HIV but now thought to have failed, leaving them facing unknown health consequences — shocked the world, horrified his peers and landed him a three-year spell in prison.

More than four years later, the spectre of He hangs over the summit as a symbol of scientific over-reach. The intervening period has, however, seen cautious optimism when it comes to treating disease: multiple clinical trials show genome editing can seemingly correct single-gene disorders, including sickle-cell anaemia.

“Technically, we’re seeing a nice progression from the first fairly crude ways of doing things to much more sophisticated, accurate and, in some cases, more efficient methods,” says Professor Robin Lovell-Badge, a developmental biologist at the Crick and chair of the summit’s organising committee.

He estimates about 70 patients have been successfully treated using the most modern genome editing methods such as Crispr. That makes regulatory approval a matter of time — and means society will have to grapple with the profound question of how and when to let the genome-editing genie out of the bottle. Issues include legality, cost and equitable access; the potential erasure of some diseases and disabilities; and human enhancement.

Human genome editing involves making changes to human DNA using chemicals that can add, delete or alter genetic material. There are broadly two types of editing: somatic and germline. Somatic genome editing involves applying the technology to a subset of a patient’s non-reproductive cells, for example blood cells.

Germline genome editing is more controversial: it is performed on early embryos and affects all cells, including egg and sperm cells. This means that, if the embryo is brought to term, all its descendants inherit a modified genome. This approach, sometimes called heritable human genome editing, is what He attempted. The World Health Organization regards somatic genome-editing as acceptable in countries with regulatory safeguards but germline-editing as posing “greater safety and ethical issues”.

One challenge is the lack of a global legal framework for DNA tinkering and, by implication, human evolution. Instead, there is a country-by-country patchwork of laws, norms, regulations and scientific moratoriums. China has tightened both its laws and regulatory oversight since He’s exploits, though summit delegates fretted that new restrictions focus too much on universities and research institutes and not enough on private clinics.

Lovell-Badge, though, mostly worries that genome editing will become the preserve of the wealthy, given that current therapies are estimated to cost upwards of six figures per patient. “The question of equitable access is a huge one,” Lovell-Badge tells me. “How do we get costs down? It’s a challenge for scientists, for economists and for everyone.”

Another question is whether genome editing could foster a lower tolerance of disability or a resurgence of eugenics. Tom Shakespeare, professor of disability research at the London School of Hygiene and Tropical Medicine, who has the genetic condition achondroplasia, said he was “not worried about eliminating disability but . . . I worry about human genome editing because of safety, questions over who can access it and the resources it might eat up.” Disability, he added, does not just have biological solutions but also social ones, such as assistive devices.

Perhaps the hardest boundary to navigate will be that between disease correction and enhancement. It is not hard to imagine a world where parents routinely design their babies for perfect health, where soldiers acquire infrared vision or humans are biologically modified to adapt to a sweltering environment. But it is easy to forget that, unlike competitive parenting, conflict and climate change have social solutions too.

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